Laser based lighting system and method

Abstract

A laser lighting system has a first laser light source, a second laser light source and a light conversion element. The outputs from the first and second laser light sources are directed to the light conversion element, which generates wavelength-converted light output in response to excitation by laser light. The first and second laser light sources generate laser light of different wavelength having different absorption characteristics within the light conversion element, such that the range of depths within the light conversion element from which wavelength-converted light is generated is different. This difference in converted output can be used to create different optical effects so that beam steering or beam shaping can be performed.

The invention claimed is: 
     
       1. A laser lighting system, comprising:
 a first laser light source configured to generate a first laser light; 
 a second laser light source configured to generate a second laser light of a different wavelength than the first laser light; 
 a light conversion element comprising different absorption rates for the different wavelengths of the first and second laser lights within the light conversion element such that the light conversion element emits substantially sideways, in a direction transverse to a depth of the light conversion element, (1) a first wavelength-converted light output in response to excitation by the first laser light and (2) a second wavelength-converted light output in response to excitation by the second laser light, wherein:
 the second laser light has a greater penetration depth into the light conversion element than the first laser light, such that 
 the second wavelength-converted light output has a larger light output area from the light conversion element than the first wavelength-converted light output; 
 
 an optical element for directing the first and the second laser lights to the light conversion element; and 
 an optical output element which shapes an output light from the light conversion element as a function of the depth from which the first and the second wavelength-converted light outputs are emitted sideways. 
 
     
     
       2. A system as claimed in  claim 1 , wherein the optical element directs the outputs from the first and second laser light sources to the same location of the light conversion element. 
     
     
       3. A system as claimed in  claim 1 , wherein the optical output element comprises a diffractive, refractive, reflective, scattering or wavelength conversion element. 
     
     
       4. A system as claimed in  claim 3 , wherein the optical output element comprises a diffraction grating that splits and diffracts light into several beams travelling in different directions. 
     
     
       5. A system as claimed in  claim 1 , wherein the optical output element comprises a specular reflector spaced from the light conversion element or a slab of material providing total internal reflection or a combination thereof. 
     
     
       6. A system as claimed in  claim 5 , wherein the specular reflector is a parabolic mirror that creates (1) a narrow beam from light emitted near a base of the parabolic mirror proximate to the optical element and (2) a broader beam from light emitted near a distal end of the parabolic mirror. 
     
     
       7. A system as claimed in  claim 5 , wherein the optical output element comprises the slab, which tapers from a distal end of the slab toward a base of the slab of material near the optical element. 
     
     
       8. A system as claimed in  claim 1 , wherein the optical output element comprises a reflector having (1) a first portion surrounding a first range of depths of the light conversion element and (2) a second portion having a different shape surrounding an adjacent second range of depths of the light conversion element. 
     
     
       9. A system as claimed in  claim 1 , wherein the light conversion element has a non-uniform absorption rate in the depth direction. 
     
     
       10. A system as claimed in  claim 1 , wherein the light conversion element has a first portion with the same absorption rate for the first laser light and the second laser light, and a second portion which has a different absorption rate for the first laser light and the second laser light. 
     
     
       11. A system as claimed in  claim 1 , wherein the light conversion element has different portions with different light output characteristics. 
     
     
       12. A system as claimed in  claim 1 , wherein the light conversion element comprises:
 scattering particles; or 
 a rough scattering outer surface. 
 
     
     
       13. A system as claimed in  claim 1 , wherein each laser light source comprises one or more laser diodes. 
     
     
       14. A system as claimed in  claim 1 , further comprising a controller for controlling the first and second laser light source output intensities. 
     
     
       15. A system as claimed in  claim 14 , further comprising a sensor providing sensor information to the controller. 
     
     
       16. An automobile front light comprising a laser lighting system as claimed in  claim 1 . 
     
     
       17. A system as claimed in  claim 1 , wherein the light conversion element comprises a uniform slab of light conversion material having a dimension in a direction of illumination that is greater than an absorption depth for at least one of the first laser light and the second laser light so that a part of the uniform slab is only excited by one of the first and the second laser light sources. 
     
     
       18. A system as claimed in  claim 1 , wherein the light conversion element has a length in a direction of illumination that is greater than its width. 
     
     
       19. A method of generating laser lighting, comprising:
 operating a first laser light source to generate a first laser light; 
 operating a second laser light source to generate a second laser light; and 
 directing the first and the second laser lights from the first and the second laser light sources to a light conversion element, thereby generating wavelength-converted light in response to excitation by laser light; 
 emitting substantially sideways from the light conversion element, in a direction transverse to a depth of the light conversion element, (1) a first wavelength-converted light output in response to excitation by the first laser light and (2) a second wavelength-converted light output in response to excitation by the second laser light, wherein:
 the second laser light has a greater penetration depth into the light conversion element than the first laser light, such that 
 the second wavelength-converted light output has a larger light output area from the light conversion element than the first wavelength-converted light output; and 
 
 shaping, by an optical output element, an output light from the light conversion element as a function of the depth from which the wavelength-converted light is generated.